See my blog post about mapping botanical gardens for some context: http://sk53-osm.blogspot.com/2013/09/a-quartet-of-botanical-gardens.html.
Suggest use of a new key garden=* or garden_feature=*. There is likely to be some overlap with types of gardens, see garden:type=*. The idea is that these can be used to provide detail of larger gardens or map isolated garden features in the broader environment.
Suggested values (note the use of a key garden is only for illustrative purposes see above:
- garden=lawn. Default surface is grass, but some other plants have been used for lawns (e.g., Camomile). See also landuse=grass for which this would either be an alternative or a refinement tag.
- garden=flower_bed. Should be a replacement for landuse=flower_bed. May needs some kind of sub/adjectival tagging especially for botanical gardens (order beds, systematic beds, Dahlia beds, ...).
- garden=pergola. Example Laburnum walk at Bodnant.
- garden=vegetable_bed. Unlikely in botanical gardens, but not uncommon in large private gardens or garden research establishments.
- garden=flower_meadow. Inclusive of many brightly-coloured flower mixes and true meadow environments.
- garden=arboretum. Only used in the context of a larger garden or feature (for instance many forests have arboreta which would not make sense to map as gardens (e.g., the Whitty Pear, Wyre Forest; N. Wales).
- garden=shrubbery. Monty Python jokes here.
- garden=compost_heap. Often rather large in big gardens
- garden=rose_garden. Example Hampton Court.
- garden=kitchen_garden. Only as feature of larger garden (for instance large country houses}}.
- garden=herb_garden. As above (& some overlap).
Features without a suggested value:
- Plantings of particular (e.g, all of one genus) trees/shrubs. A good example is Tallinn Botanical Garden. Mainly because I don't have a good single term for these areas.
- Work areas of larger gardens, with beds & greenhouses for raising plants; equipment storage etc.
- Woodland walks: encompassing the area of featured planting, paths & trees. Good example Winter Walk, Anglesey Abbey.
- Wetland features other than ponds/lakes. Notionally can use natural=wetland, but some further distinction may be needed separate from wetland=*.
Things where existing tags do the main work.
- Hothouses and other glasshouses. Note it may be desirable to use a garden tag to describe the purpose of the glasshouse: tropical, temperate, cold etc.
- Water features natural=water etc.
- paths: highway=footway etc
- Orchard and Wooded areas
- Ornamental features: statues, fountains.
- Practical amenities for visitors: benches, shelters
- Other Buildings
- Walled gardens by mapping the wall.
- Avenues of trees (tree rows)
- Specimen trees natural=tree, shrubs natural=shrub, and herbaceous perennial plants natural=plant. Tagging both latter categories should be done conservatively, and usually when the garden is particularly known for the relevant plants.
- taxon=* for any part of a garden dedicated to a particular systematically recognised plants.
- ref=* when garden areas are referenced on plans, maps and on the ground (e.g., Tallinn).
- operator=*: some features in larger gardens may be maintained by a special interest group. For instance the Walled Garden at Wollaton Park is run by the Nottingham Branch of the Hardy Plant Society; the Dahlia beds in Riga are run by the local Dahlia enthusiasts.
- access=*. Mainly relates to staff only areas of gardens separate from general access to the leisure=garden